any similarly grotesque monster having disparate parts, especially as depicted in decorative art.

3.

a horrible or unreal creature of the imagination; a vain or idle fancy:

He is far different from the chimera your fears have made of him.

4.

Genetics. an organism composed of two or more genetically distinct tissues, as an organism that is partly male and partly female, or an artificially produced individual having tissues of several species.

fabulous monster, late 14c., from Old French chimere or directly from Medieval Latin chimera, from Latin Chimaera, from Greek khimaira, name of a mythical creature, slain by Bellerophon, with a lion's head, a goat's body, and a serpent's tail (supposedly personification of snow or winter); literally "year-old she-goat" (masc. khimaros), from kheima "winter season" (see hibernation). Figurative meaning "wild fantasy" first recorded 1580s in English (attested 13c. in French).

Beestis clepid chymeres, that han a part of ech beest, and suche ben not, no but oonly in opynyoun. [Wyclif, "Prologue"]